1. Field
The present disclosure relates generally to heat pipes, and more specifically, to heat pipes with a non-uniform cross-section. Still more particularly, the present disclosure relates to heat pipes with protrusions having at least one of a tailored spacing, size, or shape.
2. Background
A heat pipe transfers heat between a heat sink and a heat source. A liquid within the heat pipe vaporizes due to heat from the heat source. The vapor travels to the heat sink and condenses into a liquid. The condensed liquid travels back to the heat source through grooves formed by protrusions within the heat pipe.
Today's communication satellites include more than 100 heat pipes per spacecraft. Almost all of these heat pipes are aluminum and ammonia heat pipes. Conventionally, the aluminum bodies of the heat pipes are made by extrusion processes. Extruded structures have a uniform cross-section throughout the pipe length.
Extrusion shapes are designed to include internal capillary grooves, an external wall or tube, and in some cases, mounting flanges. The mounting flanges are selectively located for source and sink locations. The mounting flanges are machined following extrusion. By machining the mounting flanges, welds or other joints are not present between the mounting flanges and the external wall. However, the machining process adds additional manufacturing steps and may add undesirable amounts of manufacturing time.
Following extrusion, some heat pipes may remain in substantially straight shapes. However, a significant subset of heat pipes is bent to accommodate source and sink locations.
Some of the heat pipes are bent in a planar geometry. However, the most challenging heat pipes are bent into three-dimensional shapes. In some cases, between three and ten bends are needed to accommodate the geometry. Complex three-dimensional geometries occupy a significant volume and can be hard to integrate.
The length of the heat pipes is increased to accommodate the complex three-dimensional geometry. Increasing the length of a heat pipe decreases the amount of heat the heat pipe is capable of transferring. Increasing the length of a heat pipe also increases the weight of the heat pipe.
Conventionally, to increase heat load of a heat pipe, the cross-sectional area of the heat pipe is increased, leading to a larger, heavier, extrusion. For at least these reasons, lining up flanges for mounting heat pipes can drive significant complexity, length, mass, cost, and loss of heat transport capability. Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.